Let's be clear. The Bruins the Avs faced last night is not a good team by any definition. On top of the depleted roster, Chara is returning from injury, Marchant is out, and Rask got the night off. With all this in mind, the Avs should be ashamed. Part of the problem is personnel (ie - I've always questioned the ability of a few mainstay, like Duchene's, to bounce back consistently and players in certain roles can always be upgraded), but more so I believe it has to do with the system.
The whole point of having a system is to fall back on muscle memory when emotions take hold. The problem I can see is that Roy seems content relying on the high octane talent of the forwards alone. I'm sure he has some sort of structure in place (right?!?) which the team practices, but whatever is in place not enough. You need guys to know exactly where to be in all situations. Players like Holden and Stuart can be serviceable in their roles, even in this era, but without a system you're left relying on their own creativity and skill (which they both lack) to move the puck out of the zone. If you know with near 100% certainty where your forwards and partner will be when you have one stride with the puck, you can easily look up, choose the proper option, and boom, the puck is going the other way. That's really what separates the elite defensemen in the league from the guys that seem to have some great years and then toil when the go to a lesser team (Stuart is a great example here, in fact). Defensemen like Doughty and Keith more often than not can make the proper decision without thinking and can thrive in any situation with or without a system, but indeed they really flourish with the additional structure. So yeah, in a certain sense, a personnel change viz. swapping someone like Guenin for Subban will fix some of these problems, but implementing a system is a cheaper and easier way to go. Nashville has been a model example of how you can get more out of less using this method for the past decade.
What really stood out last night was the mental fragility of the team. After the Bruins scored the first goal, the team completely just sunk and never recovered. Some games, the team will get "lucky" and respond with a quick goal, other games, the more time that go on after the deflating goal, the less likely the team is to bounce back. A system that the players could buy into would do wonders for their confidence. "Alright...we gave one up, but if we stick to what we've worked on all training camp/year, then we'll create some chances and be back in this thing." Instead, last night you saw a bunch of professionals acting like it was the Sunday morning pick-up game, essentially working as individuals and not a team.
No the sky isn't falling, but unless these issues are stamped out you'll see games here and there where the team will look competitive (eg. the game vs. Dallas), but more often games like last night's will be the norm. The main concern is that the players and coaches might be patting themselves (and whatever system they're using) on the back too much for the wins, without realizing that the underlying deficiencies could have easily reversed the outcome.